Using their long absence from the screen as a premise, this film astutely taps into the nostalgia former fans still feel for these anarchic, loveable characters while winning over new followers. And even though it's very silly, it's still hugely enjoyable.

In Smalltown America, Walter (Linz) has always felt different from his brother Gary (Segel). He has longed to meet the Muppets, his childhood heroes, and gets the chance when Gary and his girlfriend Mary (Adams) take him on a trip Los Angeles. But the Muppet Theatre is in ruin, and an evil tycoon (Cooper) is planning to tear it down and drill for oil. After meeting Kermit (Whitmire), Walter, Mary and Gary hatch a plan to save the theatre. But most of the Muppets have moved on with their lives.

The script is packed with self-referential dialog about the film itself, which often adds a freewheeling sense of humour through corny knowing winks at the audience. In fact, Segel plays the whole film staring at the camera with a wacky smirk on his face. He constantly takes us out of the story in ways Adams' more sparkly goofiness doesn't. Fortunately, the Muppets themselves continually catch us off-guard with their hilariously nutty interaction.

Kermit and Piggy (Jacobson) pick up their awkward romance without skipping a beat, and all of our favourite characters are present, even if some mainly lurk in the background. There is also a hilariously outrageous stream of cameos, from Alan Arkin and Emily Blunt to Jim Parsons and Sarah Silverman. Naturally, some of these work better than others (Dave Grohl is a favourite). But when they work, the laughter is often often uncontrollable.

Due to the post-modern jokes and some gags that fall flat (such as travelling by map), the plot never amounts to much more than cartoonish slapstick. And Walter is the most forgettable Muppet since Scooter. But seeing these long-lost characters back on screen is so much fun that it's simply impossible to dislike the film. In addition to some superbly realised songs, there are also some of the funniest movie moments in years. And it leaves us wondering why they were away for quite so long. More, please.